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skills/reviewing-performance-patterns/SKILL.md

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+---
+name: reviewing-performance-patterns
+description: Review React 19 performance patterns including memoization, re-renders, and bundle size. Use when reviewing performance or optimization.
+review: true
+allowed-tools: Read, Grep
+version: 1.0.0
+---
+
+# Review: Performance Patterns
+
+## Checklist
+
+### Re-Rendering
+- [ ] No unnecessary re-renders from prop changes
+- [ ] Using React Compiler when possible (reduces manual memoization)
+- [ ] Context split for different concerns (avoid re-render cascades)
+- [ ] Children prop pattern to prevent wrapper re-renders
+
+### Memoization
+- [ ] Manual `useMemo`/`useCallback` only when needed (React Compiler handles most cases)
+- [ ] `React.memo` used selectively for expensive components
+- [ ] Dependencies correct in memoization hooks
+- [ ] Not over-optimizing (premature optimization)
+
+### Bundle Size
+- [ ] Code splitting used for heavy components/routes
+- [ ] Server Components used where appropriate (zero client JS)
+- [ ] `'use client'` only where needed
+- [ ] Lazy loading for non-critical components
+
+### Resource Loading
+- [ ] Using preload/preinit for critical resources
+- [ ] DNS prefetch for external domains
+- [ ] Images optimized and lazy loaded
+- [ ] Fonts preloaded
+
+### Anti-Patterns
+- [ ] ❌ Array index as key (causes unnecessary re-renders)
+- [ ] ❌ Creating new objects/arrays in render (breaks memoization)
+- [ ] ❌ Excessive memoization without measurement
+- [ ] ❌ Unnecessary `'use client'` (increases bundle)
+
+For comprehensive performance patterns, see: `research/react-19-comprehensive.md`.